Surveillance cameras are used widely as security systems for residences and commercial buildings, or as outdoor security systems. Surveillance cameras include a camera body, such as a CCD camera and/or the like, and an attachment base that enables attachment of the camera body to a camera installation surface, such as a wall, a ceiling, and/or the like.
A transparent protective cover is provided on an opening in the camera body for protection from rain, gravel, and/or the like. Not only light transmittance, but impact resistance and scratch resistance are also demanded of the protective cover. Among other things, water-repellent functionality for preventing, for example, mud water from adhering to the outer surface, and moisture transmission preventive functionality for preventing condensation on the inner surface in the event of a sudden change in temperature are also demanded of the protective cover.
Resin materials are used for the base material of the protective cover mainly for product cost purposes. In addition, readily moldable resin materials, such as polycarbonate, acryl, and/or the like, are used as base materials to obtain protective covers of diverse shapes. Resin base materials are highly moldable, and they can be molded into various shapes, such as hemispherical (dome-shaped), semicylindrical, box-shaped, and/or the like.
Surveillance cameras are often installed outdoors, and are thus found in environments where the lens is prone to contact with water drops. When a water drop adheres to the lens, the water drop causes light to refract, and consequently, the obtained image is severely and adversely affected.
In recent years, a technique where a hydrophilic coating including a photocatalyst is applied to the camera cover surface has been receiving considerable attention as a method of addressing the above. With this technique, the functionality of the hydrophilic coating that turns water drops into a thin film of water serves to minimize the impact of water drops on the obtained image. Furthermore, even if dirt were to adhere, this film of water would suspend the dirt from the cover surface, and one would be able expect a cleaning effect where the suspended dirt is automatically removed by rain, for example.
Japanese Patent Application Laid-Open No. 2003-78788 (hereinafter referred to as Patent Literature 1) discloses an outdoor television camera having a photocatalyst film formed on the camera cover surface. The camera cover disclosed in Patent Literature 1 is configured in such a manner that its surface is coated with a hydrophilic photocatalyst film, and dirt is cleaned by rain.